1. Field of the Invention
The present invention relates to photography and, more particularly, to an improved bearing block mount for a photographic fluid spreading apparatus for processing a self-developing type film unit.
2. Description of the Prior Art
Photographic apparatus for spreading a fluid processing composition across an exposed photosensitive sheet element to initiate formation of a visible image by a diffusion-transfer type process is well known in the art. A self-developing type camera having a photographic processing apparatus incorporated therein, designed to be employed with a film unit including a photosensitive image-recording medium in the form of a sheet like element, a second image-receiving element superposed with the photosensitive element and a rupturable container or pod including the fluid processing composition located at one end of the film unit in position to discharge its fluid contents between the two elements for distribution therebetween in response to an application of compressive pressure by the photographic processing apparatus upon the container or pod is also well known in the art. Generally, processing of the film unit is achieved by moving the film unit, container or pod foremost, between a pair of pressure-applying spreader elements preferably juxtaposed rollers having sheet-contacting surfaces in engagement with opposing surfaces of the film unit passing therebetween to distribute the processing composition in a layer between the superposed elements. A typical example of a film unit having all of the especially designed film structure necessary to carry out the aforementioned process as it is progressively advanced between the spreader elements may be found in U.S. Pat. No. 2,543,181 entitled "Photographic Product Comprising A Rupturable Container Carrying A Photographic Processing Liquid", issued to E. H. Land on Feb. 27, 1951 and assigned in common herewith.
In general, the quality of the final image presented to an operator upon a surface of a processed photographic film unit critically depends upon a proper covering of fluid processing composition over a predetermined area between the superposed elements of the film unit in a substantially uniform layer effectively distributed by the spreader elements as the film unit is progressively advanced therebetween. Prior art processing apparatus have employed as spreader elements a pair of juxtaposed non-rolling members, a pair of juxtaposed rotatable members or rollers, and a pair of juxtaposed pressure surfaces including one non-rolling member and one rotatable member. The film units have been generally processed by manually withdrawing them, subsequent to exposure, one at a time between juxtaposed spreader elements or automatically advancing them between a pair of motor driven processing rollers for effecting the processing composition and spreading functions. In either arrangement it is equally important for the sheet-contacting surfaces of the spreader elements to be positioned and retained in precise parallelism with each other and at least one of the juxtaposed sheet-contacting surfaces of the spreader elements must be biased in the direction of the other under a predetermined force to provide sufficient compressive pressure against opposing surfaces of the film unit to rupture the container or pod such that its fluid contents are distributed between the superposed element as the film unit is progressively advanced between the spreader elements. Furthermore, the sheet-contacting surfaces of the spreader elements are preferably provided with a predetermined minimum spacing between the sheet-contacting surfaces to facilitate an initial introduction of a leading edge of the film unit therebetween. While most or all of the foregoing functional requirements have been effectively fulfilled by prior commercially available embodiments of processing apparatus incorporated within known photographic cameras of the self-developing type, there is still a need for an improved processing apparatus from the standpoint of providing a relatively simple design which substantially reduces the manufacturing and assembly costs without sacrificing any of the aforementioned functional requirements.
It is well known that frictional resistance to a sliding motion is substantially greater than a frictional resistance to a rolling motion. If a film unit slides between opposing surfaces being pressed together by a normal force, a frictional force resisting the motion must be overcome. This is of particular concern in a case in which a self-developing type film unit is manually withdrawn for processing between a pair of juxtaposed non-rolling type spreading elements formed of sheet metal parts of the type similar to that disclosed in U.S. Pat. Nos. 3,485,155; 3,498,196 and 3,537,371 wherein the frictional force opposing the sliding movement of the film unit between the spreader elements is arduous and often leads to tearing or mistracking of the film unit in an effort to withdraw the film unit between the spreader elements. Therefore, the use of rollers as substitute spreader elements despite the increased cost involved in incorporating them into a low priced self-developing type photographic camera was deemed necessary. A typical example of a substantially reduced cost roller type processing apparatus for use in such a low priced self-developing type camera is disclosed in U.S. Pat. No. 3,745,904 issued to Herbert A. Bing et al., on July 17, 1953 entitled "Low Cost Roller Type Photographic Fluid Spreading Apparatus". The processing apparatus disclosed therein is directed toward substantially reducing the prohibitive cost of previously known roller type processing apparatus in a low priced camera and thereby substantially lowering the frictional force resisting the movement of the film between the spreader elements by substituting the rolling motion of the rollers for the sliding movement of the film unit between the non-rolling spreader elements to distribute the fluid processing composition. The processing apparatus disclosed therein comprises a pair of rotatable juxtaposed rollers mounted between a pair of spaced rigid bearing blocks having recesses for receiving opposing ends of the rollers therein and spaced to establish a predetermined minimum spacing between the sheet-contacting surfaces of the rollers to facilitate an introduction of the leading edge of the film unit therebetween. Each of the bearing blocks includes a circular recess vertically aligned in superposed relation with an elongated recess for rotatably supporting the opposing ends of the rollers therein. The circular recess supports the uppermost roller in a fixed position against translational movement upon the bearing blocks. The elongated recess rotatably supports the lowermost roller upon the bearing blocks. The length of the elongated recess limits the distance through which the lowermost roller may be displaced from the uppermost roller as the film unit is advanced therebetween for processing. A platform member is adapted to receive the bearing blocks with the rollers rotatably mounted therebetween. The bearing blocks are coupled to the platform member by slidably inserting the bearing blocks into respective channels provided therefor. An especially configured U-shaped load spring element is associated with each of the bearing blocks to resiliently urge the rollers towards each other whereby compressive pressure is applied to opposing surfaces of the film unit by the sheet-contacting surfaces of the film unit for rupturing the container and distributing the released fluid processing composition between the superposed elements. One end of each spring element is mounted beneath each elongated recess and is retained in continuous frictional engagement in bearing against each opposing end of the lowermost roller whereby the lowermost roller is yieldably urged thereby towards the uppermost roller to apply compressive pressure upon the opposing surfaces of the film unit. The lowermost roller is displaced away from the uppermost roller by the film unit as it passes between the rollers. The lowermost roller is moved within the elongated recess against the urging of the spring elements and the ends of the respective spring elements in contact therewith are deflected towards the platform by a distance great enough to enable the film unit to advance therebetween with sufficient pressure being applied to opposing surfaces of the film unit to rupture the pod and spread the released processing composition between the superposed sheet elements of the film unit.
It is well known in the art that the speed at which the film unit is progressively advanced between the rollers critically effects the distribution of the fluid processing composition between the superposed elements i.e., the thickness of the layer of the processing composition and thereby the final development of the photographic print. For example, if the film unit is advanced too rapidly between the rollers, the layer of processing composition deposited between the superposed elements may be too thin and result in a poor quality photographic print. Furthermore, if the film unit is advanced too slowly, the distribution of the processing composition between the superposed elements may be incomplete as the limited supply of fluid included in the container may be exhausted before the processing composition has been uniformly distributed in a layer between the superposed sheet elements. One of the major drawbacks in producing a self-developing camera of the type in which the film unit is manually withdrawn between the spreader elements is the inability to establish the highly unpredictable linear rate at which the film unit shall be withdrawn between the rollers by the operator. Typically, the desired linear rate or pull rate at which the film unit should be withdrawn between the rollers is within the range of 6 to 9 inches per second. However, it has been established that operators generally pull film units as rapidly as 105 inches per second and as slowly as 3 inches per second with a greater majority of the operators pulling the film unit at a rate exceeding 50 inches per second. To compensate for the reduction in friction offered by substituting rollers for the non-rolling spreader members previously employed in such a processing apparatus, the spring elements are deliberately designed to remain in continuous engagement with the opposing ends of the lowermost roller to bear thereagainst and thereby offer at least some resistance to rotation by inducing a drag load against the roller to substantially reduce the speed at which the majority withdraw the film. However, an intentionally induced drag load is not desirable in all designs of all self-developing type cameras and is particularly undesirable in automatic cameras which incorporate motor driven processing spreader elements or rollers to effect the processing composition dispensing and spreading functions.
A processing apparatus including a pair of rollers driveably coupled to a motor drive system for spreading a processing fluid between a pair of sheet materials to initiate formation of a visible image in a film unit is known in the art. The apparatus comprises the pair of rollers, a U-shaped support for rotatably supporting one of the rollers, a pair of bearing blocks for rotatably supporting the other roller and a flat, low rate spring having a plurality of leaf-like members. The U-shaped support includes an open ended elongated slot in each leg thereof which is adapted to slidably receive one of the bearing blocks. The spring engages the base of the U-shaped support and each of the bearing blocks to resiliently urge the two bearing blocks and their associated movable roller towards the other fixed roller rotatably supported on the U-shaped support. A pair of plastic bearings installed in each of the legs for rotatably supporting the fixed roller cooperate with the bearing blocks which function as a keeper for the other fixed roller. Each end portion of the spring is adapted to be received in a recess provided therefor in each of the bearing blocks for applying an upward force to the bearing blocks to bias the roller associated therewith towards the fixed roller. As the film unit enters a gap between the rollers, its thickness results in the bearing blocks being moved downwardly within the elongated slot against the resiliency of the spring.
While the above-noted structure substantially reduces the cost of the processing apparatus by substituting bearing blocks and plastic bearings for metal ball bearing assemblies; there is still room for considerable improvement. For example, the spreader elements are rotatably supported on separate elements of the apparatus with its attendant tolerance stack-up disadvantages. The spring element is a low rate spring having a relatively complex configuration which may be relatively expensive for use in a photographic camera developed for large quantity production. It would appear that a number of parts involved in rotatably supporting the rollers may be further reduced such that remaining parts not only perform their function but also the functions of the parts which were eliminated.
Exemplary disclosures of relatively recent developments in such cameras and film units for use therewith are found in U.S. Pat. No. 3,415,644 entitled "Novel Photographic Products and Processes," U.S. Pat. No. 3,766,842 entitled "Photographic Film Processing Apparatus" and U.S. Pat. No. 3,714,879 entitled "Reflex Camera" all of which are assigned to the assignee of the present invention. When the film units described in the first two of these U.S. Patents are passed between a roller type processing apparatus, a pod-like container is ruptured and a fluid processing composition including an opacifying agent is spread as a layer to provide a background for the photosensitive transfer image evolved during its development outside of the camera. Because the opacifying agent serves as a light shield during the diffusion transfer development process, it is important that the spread of the fluid be properly regulated to insure a smooth and continuous spreading of the processing composition between the sheet elements of the film unit. Such film units are processed in a highly effective manner in which the film unit is generally automatically advanced subsequent to exposure at a predictable predermined linear rate. At least one of the spreader rollers constitutes a drive roller in that it has a spur gear axially coupled thereto which in turn is connected to the motor through an appropriate gear train. Generally, a second one of the pair of rollers constitutes a driven roller in that it is driven by the frictional engagement with the film unit as it is advanced by the drive roller therebetween.
The electrical energy for operating the various automatic systems and the motor drivably coupled to the drive roller is provided by a battery having a limited power supply which upon being substantially diminished can render the camera inoperative. The battery may be included in the camera or as a member of an assemblage of discrete film units stored within a container or cassette of the type disclosed in U.S. Pat. No. 3,967,292 entitled "Film Assemblage Including A Hermetically Sealed Battery" issued on June 29, 1976 to R. M. Delahunt and assigned in common herewith. It is conceivable that by incorporating a processing apparatus of the type disclosed in the aforementioned U.S. Pat. No. 3,745,904 having the drag load deliberately incorporated into its design, an unnecessary amount of energy may be spent in overcoming that drag load. Should the supply of energy be diminished enough to render the camera inoperative before the film supply in the cassette is exhausted, the remaining film units cannot be exposed and processed. Of more serious concern, is the potential damage to the driving components of the roller if any energy supply failure should develop during a partially completed processing cycle. There may be a tendency by some unknowing photographer to pull the film unit manually through the processing spreader elements to remove it from the camera. By substantially reducing the frictional resistance to rotation, battery energy waste and possible overloading of the drive system may be avoided. Therefore, the processing apparatus disclosed in the aforementioned U.S. Pat. No. 3,745,904 may not be suitably adapted to cooperate with an automatic motor power drive system as it would include a compromised drawback to the drive system's operation which would off set the reduction in cost and the simplicity in its design which is associated with producing the prior art device.
The processing apparatus presently employed in the automated reflex camera disclosed for example in the aforementioned U.S. Pat. No. 3,714,879 is similar to the type disclosed in the aforementioned U.S. Pat. No. 3,766,842. The apparatus comprises first and second rotatably mounted juxtaposed elongated rollers which are yieldably urged one towards the other. A pair of annular collars provided on the first roller define a minimum gap between the rollers to facilitate the initial introduction of a leading edge of a film unit therebetween. The first roller is adapted to be selectively driven by a motor of the camera system and when so driven, the annular collars impart a rotary motion to the second roller. Opposing ends of the first and second rollers are rotatably supported within ball bearing assemblies. The second roller consists of a tubular roller shell rotatably mounted upon an elongated shaft extending therethrough and supported at each end by one pair of the spaced ball bearing assemblies which are disposed within the tubular roller shell. An elongated vertically disposed slot is provided to receive opposing ends of the elongated shaft therein whereby the shaft is supported in substantial parallel relation with the first roller for translational movement toward and away from the first roller. A specially configured, elongated, torsion spring is mounted in position to underlie the shaft extending through the second roller. Opposite ends of the torsion spring are configured to seat in appropriately positioned complementary annular recesses provided on the shaft so that the force of the spring remains continually engaged with the shaft to urge the second roller or tubular shell toward the first roller and present thereby a friction load to overcome. It is conceivable that instead of providing a processing apparatus with ball bearing assemblies provided for rotatably supporting a pair of rollers and separate structure, e.g., annular collars, for predeterminately spacing the rollers from each other one could provide a single structure for performing both functions.
Although many of the aforementioned traditional and commercially available processing apparatus have fulfilled the functional and operational requirements for processing a self-developing type film unit, it is of the utmost importance that the cost of such an apparatus be kept as low as possible. One solution to keeping the cost of the processing apparatus to a minimum is to reduce the number of parts in the apparatus such that they not only perform their function but also the functions of the parts which were eliminated.
Accordingly, an object of the present invention therefore, is to provide an improved processing apparatus of the film advancing type for spreading a fluid processing composition in a substantially uniform layer between superposed sheet elements of a self-developing type film unit at least one of which forms part of a film unit.
It is another object of the invention to provide a relatively low-cost processing apparatus employing roller-type spreader elements which is compact and easy to assemble.
A further object of this invention is to provide a processing apparatus of the type indicated which may be utilized to replace a processing apparatus currently employed in commercially available cameras without requiring any alterations to be made to other elements of such cameras and which may be fabricated in a relatively inexpensive operation.
Other objects of the invention will in part be obvious and will in part appear hereinafter. The invention accordingly comprises the apparatus possessing the construction, combination of elements, and arrangement of parts which are exemplified in the following disclosure and the scope of the application which will be indicated in the claims.